Thursday, October 28, 2010

"Blue Straggler" Stars Cannibalize to Stay Young

In a paper published last week in the journal Nature, the researchers report a strong link between the total number of blue stragglers and the mass of a cluster's core, the dense central region of stars.

"Cluster cores containing more stars contain more blue stragglers," Knigge said. And the more massive a cluster, the higher number of binary pairs it contains.

"We see a lot of blue stragglers even in massive cores that have low collision rates," he added.

Michael Rich, an astrophysicist at the University of California, Los Angeles, said the paper reports "the first sensible correlation" between the number of blue stragglers and a property of globular clusters, in this case, core mass.

Rich noted that a 2007 study published in the journal Astronomy and Astrophysics used different methods to also suggest that blue stragglers arise from binary pairs instead of collisions.

"As the understanding of blue stragglers increases, it becomes possible to use these stars to understand important things about the origins of stellar populations," Rich added.

Life of a Straggler

Knigge and his team are now engaged in work to determine whether the binary pairs that tend to form blue stragglers have special life histories, such as close encounters or collisions with other binaries or single stars.

Study co-author Alison Sills, an astrophysicist at McMaster University in Ontario, is also investigating the way binaries can transform themselves into blue stragglers and what those blue stragglers should look like.

Finally, Knigge said, further observation with tools such as the Hubble Space Telescope should help confirm the team's findings.

"Determining parameters like spin rates and abundances for a large number of blue stragglers will definitely help unravel their origin," he said.